For MY96 Subaru introduced factory fitted immobilisers. These are of the ‘transponder key’ type, where the key contains a chip which the immobiliser ‘talks to’. The engine will only start if the immobiliser system recognises the chip inside the key. Non of the factory fitted immobiliser systems can be removed or bypassed. The transponder key immobilisers work totally independently of any alarm which is fitted to the donor Subaru, and no user interaction is required. Having an immobiliser does not rule out using an engine in a VW conversion. It does mean that you have to be VERY careful when buying an engine that it includes all the immobiliser components, and that they are a matched set (i.e. from the same donor vehicle). A factory fitted immobiliser also means a small increase in the amount of work involved in converting the Subaru wiring harness for use in a VW.

How to Tell Whether a Subaru has a Transponder Key Immobiliser System:

A quick guide as to whether a Subaru has a transponder key immobiliser immobiliser is to look for the immobiliser LED in the dash instrumentation. This is the LED which flashes when immobilised to warn potential thieves. In Early Subaru’s this is easy to spot. There is a key shaped symbol with a standard 5mm red LED sticking through it, as shown to the left:

In later models the LED is much harder to spot, especially if you can not power up the electrics. This is because the symbols can’t be seen in later models until they light up. The picture below shows the ‘hidden’ lights in a dismantled instrument panel by back lighting them:

The presence of an immobiliser light in the dash is not a definitive indicator of whether the Subaru has a transponder key system. It is very likely that light is still present in the dash, especially in the later models, on models with no immobiliser too. Read on for better ways of telling whether a transponder key immobiliser system is fitted.

Transponder Key Immobiliser Types:

There are two types of transponder key immobiliser system used in Subaru’s between MY96 and MY07. Those from MY96 - MY99 used a fixed code system, which means the keys can be cloned by a lock smith with specialist equipment, as the code from the key can be read, and programmed into a new key. From MY00 - MY07 an encrypted transponder was used, which prevents keys from being cloned.

The transponder key immobiliser system was introduced to different Subaru models in different Subaru markets at different times. A rough guide to which system was fitted to which models where and when is as follows, for --> MY07:

From MY08 --> the transponder key system has apparently changed again, to an even more secure type.

All Subaru’s in the above table, with one possible exception, do not require the dash instrumentation to be connected to get the engine to run, as some engines (such as VW’s TDi’s) do. The exception is MY04 --> Legacy models. These are very likely to require the dash instrumentation and maybe other ECU’s connecting too before the engine will run. The same also applies to all MY08 --> Subaru models.

To see more information about each type of transponder key system. please click one of the following links:

If buying an engine with a transponder key immobiliser system, it can’t be stressed strongly enough how important it is to make sure you buy a matching set of immobiliser components. By ‘matching’, we mean you are 100% certain that the engine ECU, immobiliser ECU, and key are from the same car. If you are buying a complete, running car, then you can easily check that the components are matched. If the engine runs for more than 10 seconds, then they are matched. However, if you are buying components from a breaker, you have to be super careful. Try the ker in the car’s locks to be sure it really is the right one for the car, and remove the ECU’s yourself if possible, so you know you have a matched set. It is possible to have the ECU’s programmed by a Subaru dealer to accept a new key, if you buy a set with no key, or an incorrect key. However, it is best to avoid this situation by making sure it’s a matched set in the first place. Note that to program the ECU’s to accept a new key, the dealer HAS TO HAVE the original car’s VIN and registration numbers, and the Subaru diagnostic system must be fully intact in your VW. Without any of these, they will not be able to help you, and your engine and immobiliser ECU’s are scrap. Programming for new keys can only be done by official Subaru dealers. The programming itself is reasonably priced, but a new key is VERY expensive. The dealer will need your complete vehicle, with the engine installation ready to run except for the key in order to carry out the programming. If you need a transponder key, get in touch with us, as we may be able to help source one for a more reasonable price. However, our help can not go beyond that unless we happen to have a vehicle in with identical wiring to yours available at the time. You will have to the the vehicle to a Subaru dealer yourself, and persuade them whey they should plug into a VW. A neat, profesional looking engine installation will probably help a lot here. Their diagnostic equipment is very expensive, and it is not unreasonable for them to refuse to plug in to a converted VW - especially if your wiring looks a mess. For details on the immobiliser components in each of the two transponder key systems, see the links above.

Thatcham Immobiliser approval:

If you are in the UK it may be of interest that neither of Subaru’s transponder key immobiliser systems have Thatcham approval, so will not enable the user to get reduced insurance. In terms of security they are both very similar to Thatcham Category 2 specification, and the lack or approval is probably due to them never having been tested, rather than having been tested and failed. Both of the system types, and especially the cryptographic one, are at the more secure end of factory fitted immobilisers, as demonstrated by the fact that no aftermarket hardware has been developed to bypass or remove them. Such devices are available for many other car’s immobilisers, many of which are Category 2 rated. Most UK Subaru’s from about MY00 --> have Thatcham Category 1 alarm immobilisers as standard (see http://www.thatcham.org/security/pdfs/categories/PassengerCarCAT1.pdf), but this is nothing to do with the transponder key system. They have a separate Category 1 alarm immobiliser system too, and the two work independently.